Pharmaceutical and nutritional supplement dosage forms intended for oral administration are typically provided in solid form as tablets, capsules, pills, lozenges or caplets. The tablet form is swallowed whole, chewed in the mouth, or applied sublingually. Absorption of the active moiety depends upon its release from the dosage form and may be controlled by several different technologies.
Chewable delivery systems are often used in the formulation of pharmaceuticals. Chewable systems are often employed in the administration of pharmaceuticals, where it is impractical to provide a tablet for swallowing whole. The act of chewing increases the surface area of the available active ingredient and may increase the rate of absorption by the digestive tract. Chewable systems are also advantageous where it is desirable to make an active ingredient available topically to the mouth or throat areas for both local effects or systemic absorption. Chewable dosage forms are also utilized to ease drug administration in pediatric and geriatric patients.
Palatability and "mouth feel" are important characteristics to be considered in providing a dosage form, or matrix, for an active pharmaceutical or medicinal. Unfortunately, many pharmaceuticals and other active ingredients have a bitter or otherwise unpalatable taste, or an unacceptable mouth feel, due to the grittiness or chalkiness of the compound, or both. These characteristics make it difficult to incorporate such active ingredients into the current state of the art for chewable dosage forms because the objectionable taste and/or mouth feel make it less likely to obtain compliance by the user.
As a result, several approaches have been tried in attempting to overcome these problems. The poor taste of a pharmaceutical or other active ingredient may be masked by using suitable flavoring compounds and/or sweeteners. Encapsulation of the active ingredient may also serve to mask bitterness and other undesirable tastes. However, these approaches do not affect the physical state of the dosage form currently employed in the art. For example, chewable vitamin tablets are typically prepared as a compressed, compacted tablet, incorporating one or more active ingredients (e.g., vitamins), a sweetener and flavoring agent to mask the taste of the active ingredients, and a binder, typically microcrystalline cellulose.
Generally, chewable tablets are made by direct compression of a mixture of tableting compounds including the active ingredient, flavorant, binders, etc. The mixture is fed into a die chamber of a tablet press and a tablet is formed by direct compaction. Hardness of the resulting tablet is a direct function of the compression pressure employed. A softer tablet, having an easier bite-through, may be prepared by adding a disintegrant, such as alginic acid, to the pre-tablet mix. Alternatively, a softer tablet may be formed by employing reduced compression pressures. In either case, the resultant tablet is softer, fragile, brittle and easily chipped. See U.S. Pat. No. 4,327,076, incorporated herein by reference. Compressed, chewable tablets generally suffer from less than desirable mouth feel, i.e., chalkiness, grittiness, and a dry, powdery taste. Antacid tablets, e.g., Tums.RTM. manufactured by SmithKline Beecham Corp., Pittsburgh, Pa. and Rolaids.RTM. manufactured by Warner Lambert of Morris Plains, N.J., are each examples of typical compressed chewable tablets.
Attempts have been made to reduce the grittiness and/or chalkiness of the compressed tablet by coating particles of the active ingredient with oils or fats, which coat the particles prior to incorporation into the delivery system. See U.S. Pat. Nos. 4,327,076 and 4,609,543, incorporated herein by reference. In this way, the grittiness or chalkiness of the particles is masked by the oil or fat while the particles are in the mouth. In addition, tablet softness is improved. After swallowing, the oil or fat is removed and the particle can be absorbed by the digestive system. However, the addition of fats or oils to the pre-tablet mix can cause the tableting ingredients to adhere to the die chamber and cause a reduction in the binding action of the binders present in the mix.
Other techniques for providing a chewable delivery system involve the use of a gum base. Gum bases are insoluble elastomers which form the essential element for chewing gum. The gum base is typically blended with one or more sweeteners to obtain a confectionery gum. A coating containing the active ingredient is then applied over the confectionery gum. As the dosage form is chewed, the coating fractures and/or is dissolved in the mouth and swallowed. This approach is currently employed with gum-based products manufactured by Schering Plough HealthCare, such as aspirin (Aspergum.RTM.); antacids (Chooz.RTM.); and laxatives (Feenamint.RTM.). Dosage forms of this nature (especially aspirin) may not provide the active ingredient as a bioavailable agent to the same extent as an oral tablet dosage form. See "Relative Bioavailability of Aspirin Gum", J. Pharm. Sci., 70:1341 (1981).
Another type of chewable delivery system incorporates the active ingredient into the gum base. Nicotine polacrilex (Nicorette.RTM.) distributed by Marion Merrell Dow, is an example of this technology.
Other delivery systems involve the used of layered, non-homogeneous structures.
Another chewable delivery system is based on a nougat-type, chewy tablet. Such tablets generally employ a base of corn syrup (or a derivative). Such tablets are prepared as a confectionery, i.e., the corn syrup is cooked with water and a binder such as soy protein. One example of such a tablet is Tempo.RTM. antacid tablets, distributed by Thompson Medical Co., Inc., of West Palm Beach, Fla.